1. Field of the Invention
The present invention relates to a liquid crystal driving apparatus for driving a dot-matrix type liquid crystal display panel.
2. Description of the Related Art
Conventionally, a dot-matrix type liquid crystal display panel is generally used as a display unit of, e.g., a portable compact TV receiver or a compact electronic calculator. FIG. 1 shows the arrangement of a driving circuit of such a liquid crystal display panel. Referring thereto, reference numeral 11 denotes an N.times.M-dot dot-matrix type liquid crystal display panel (LCD); numeral 12, a segment driver for driving a segment electrode of the display panel 11; 13, a common driver for driving a common electrode of the display panel 11; 14, an A/D converter for quantizing an analog video input signal in units of pixels of N.times.M dots; and 15, a timing signal generator for sending timing signals to the segment driver 12, the common driver 13, and the A/D converter 14.
The A/D converter 14 quantizes an analog video signal in units of pixels of N.times.M dots in synchronism with the timing signal from the generator 15 and sends the quantized signal to the segment driver 12. The driver 12 forms a gradation signal on the basis of the digital data from the A/D converter 14 and drives the segment electrode of the display panel 11. As a result, in the display panel 11, a common electrode selected by the common driver 13 and a segment electrode portion corresponding to the common electrode are driven at a gradation level according to the video signal.
In the liquid crystal driving apparatus having the above arrangement, one frame of a TV image is displayed every 17[ms] (=1/60 [s]). Therefore, the response speed of the liquid crystal display panel is naturally required to be much higher than 17 [ms].
Response speeds of currently available liquid crystal display panels, however, are about 50 to 100 [ms], i.e., longer than the display period of one frame of a TV image. Therefore, an afterimage undesirably appears upon moving image displays in which the image changes rapidly.